Hydrorefining of petroleum crude oil and catalyst therefor



United States Patent HYDROREFINING OF PETROLEUM CRUDE OIL AND CATALYST THEREFOR William K. T. Gleim, Island Lake, 111., assignor to Universal Oil Products Company, Des Plaines, 11]., a corporation of Delaware No Drawing. Filed Aug. 31, 1964, Ser. No. 393,341

9 Claims. (Cl. 252439) The invention herein described is adaptable to a process for the hydrorefining of heavy hydrocarbon fractions and/or distillates. More particularly, the present invention is directed toward a method of preparing a novel hydrorefining catalytic composite, which composite is especially advantageous in treating petroleum crude oils and topped, or reduced crude oils for the removal of organo-metallic contaminants and the conversion of pen- 3,297,589 Patented Jan. 10, 1967 presence of large quantities of asphaltenic material and organo-metallic compounds interferes considerably with the activity of the catalyst with respect to the destructive removal of the nitrogenous, su-lfurous and oxygenated compounds, which function is normally the easiest for the catalytic composite to perform to an acceptable degree. Therefore, it is highly desirable to produce a hydrocarbon mixture substantially free from asphaltenic material and organo-metallic compounds, and which mixture is substantially reduced with respect to nitrogen and sulfur concentratron.

A wide variety of heavy hydrocarbon fractions and/or distillates may be treated, or decontaminated effectively through the utilization of the catalytic composite prepared by the method of the present invention. Such heavy hydrocarbon fractions include full boiling range crude oils, topped or reduced crude oils, atmospheric distillates, vis-breaker bottoms product, heavy cycle stock from thermally or catalytically-cracked charge stocks, heavy vacuum gas oils, tar sand oils, etc. A Wyoming sour crude oil, having a gravity of 23.2 API at 60 F.,

. is contaminated by the presence of 2.8% by weight of jected. Among the non-metallic impurities are nitrogen,

sulfur and oxygen which exist as heteroatomic com.- pounds, nitrogen probably being most undesirable because it effectively poisons various catalytic composites which may be employed in the conversion of petroleum fractions; in particular, nitrogen and nitrogenous compounds are known to be effective hydrocracking suppressors. Both nitrogenous and sulfurous compounds are objectionable because combustions of fuels containing these impurities results in the release of nitrogen and sulfur oxides which are noxious, corrosive, and present a serious problem with respect to atmospheric pollution. With respect to motor fuels, sulfur is particularly objectionable because of odor, gum and varnish formation and significantly decreased lead susceptibility.

In addition to the foregoing described contaminating influences, petroleum crude oils and other heavy hydrocarbonaceous material contain high molecular weight asphaltenic compounds. These are non-distillable, oilsoluble coke precursors which may be complexed with sulfur, nitrogen, oxygen and various metals. Of the metallic contaminants, those containing nickel and vanadium are most common although other metals including iron, copper, lead, zinc, etc., are often present. Although the metallic contaminants may exist within the hydrocarbonaceous material in a variety of forms, they are generally present as organo-metallic compounds of relatively high molecular weight, such as metallic porphyrins and the various derivatives thereof. A considerable quantity of the organo-metallic complexes are linked with asphaltenic material and become concentrated in the residual fraction; other organo-metallic complexes are volatile, oil-soluble, and are, therefore, present in the lighter distillate fraction. A reduction in the concentration of the organo-metallic complexes is not easlly achieved, and to the extent that the crude oil, reduced crude oil, or other heavy hydrocarbon charge stock derived therefrom becomes suitable for further processing. Notwithstanding that the concentration of these organometallic complexes may 'be relatively small in distillate oils, for example, often less than about 10 p.p.m., calculated as if the complex existed as the elemental metal, subsequent processing techniques are adversely affected thereby. With respect to a process for hydrorefining or treating of hydrocarbon fractions and/ or distillates, the

sulfur, 2700 p.p.m. of total nitrogen, approximately 100 p.p.m. of metallic complexes, computed as elemental metals, and contains a high boiling, pen'tane-insoluble asphaltenic fraction in an amount of about 8.4% by weight. A more difficult charge stock to convert into useful liquid hydrocarbons, is a crude tower bottoms product, having a gravity, "API at 60 F., of 14.3, and contaminated by the presence of 3.0% by weight of sulfur, 3830 p.p.m. of total nitrogen, p.p.m. of total metals and about 10.93% by weight of asphaltenic compounds. Similarly, an atmospheric tower bottoms product, having a gravity of 7.0 API at 60 F., is contaminated by 6,060 p.p.m. of total nitrogen, 4.05% by weight of sulfur, more than 450 ppm. of total metals, and contains an asphaltenic fraction in an amount of 24.0% by weight. As hereinbefore stated, asphaltenic material is a high molecular weight hydrocarbon mixture having the tendency to become immediately deposited within the reaction zone and other process equipment, and onto the catalytic composite in the form of a high molecular weight residue. Furthermore, the presence of excessive quantities of asphaltenes, in addition to the foregoing described contaminating influences, appears to inhibit the activity of the catalyst in regard to the destructive removal of sulfur and nitrogen. The object of the present invention is to provide a catalytic composite suitable for utilization in a process for hydrorefining heavy hydrocarbonaceous material, and particularly full boiling range crude oils, and topped or reduced crude oils. The use of the catalyst of the present invention affords the utilization of a fixed-bed hydrorefining process, which type of process has not been considered feasible due to the deposition of coke and other gummy carbonaceous material. Although the difficulties encountered in a fixed-bed catalytic process are at least partially solved by a moving-bed or slurry operation, wherein the finely-divided catalytic vcomposite is intimately admixed with the hydrocarbon charge stock, the mixture being subjected to therdesired operating conditions, the slurry process tends to result in a high degree of erosion, thereby causing plant maintenance and replacement of process equipment to be difficult and expensive. Furthermore, a slurry operation has the disadvantage of having a relatively small amount of catalyst being admixed with relatively large quantities of asphaltenic material. In other words, too few catalytically active sites are made available for immediate reactions, with the result that the asphaltenic material has the tendency to undergo thermal cracking, resulting in large quantities of light gases and coke. These difliculties are ride composite.

in turn at least partially avoided through the utilization of a fixed-fluidized process in which the catalytic composite is disposed within a confined reaction zone, being maintained, however, in a fluidized state by exceedingly large quantities of a fast-flowing hydrogen-containing gas stream. Difiiculties attendant the fixed-fluidized bed process reside in a large loss of catalyst, removed from the reaction zone with the hydrocarbon product efiluent, the relatively large quantities of catalyst necessary to effect proper contact between the as-phaltenic material and active catalyst sites, etc. The particularly prepared hydrorefining catalyst of the present invention, utilizing a refractory inorganic oxide carrier material, permits effecting the process in a fixed-bed unit without incurring the difliculties hereinbefore described. The catalyst of the present invention is particularly advantageous in effecting the removal of organo-metallic compounds while simultaneously converting pentane-insoluble material into pentane-soluble liquid hydrocarbons.

In a broad embodiment, the present invention relates to a method of preparing a hydrorefining catalyst, which method comprises impregnating a refractory inorganic oxide with a decomposable vanadium compound, treating the impregnated inorganic oxide with a sulfurous compound selected from the group consisting of sulfur monochloride, sulfur dichloride and mixtures thereof, and calcining the resulting inorganic oxide-vanadium trichlo- A more limited embodiment of the present invention affords a method of preparing a hydrorefining catalyst which comprises impregnating a composite of silica and alumina with ammonium vanadate, treating the impregnated composite with sulfur monochloride at a temperature not above 138 C., and calcining the resulting alumina-silica-vanadium trichloride composite at a temperature within the range of from about 150 F. to about 500 F.

As hereinabove set forth, the catalyst of the present invention is especially advantageous for use in a process for hydrorefining an asphaltene-containing hydrocarbon charge stock, which process comprises reacting said charge stock wit-h hydrogen in contact with a catalytic composite of an alumina-containing inorganic oxide and vanadium trichloride, at a temperature of from about 225 C. to about 500 C. and under a pressure within the range of about 500 to about 5000 p.s.i.g.; the process being further characterized in that said catalytic composite is prepared by impregnating an alumina-containing inorganic oxide with a decomposable vanadium compound, treating the impregnated inorganic oxide with a sulfurous compound selected from the group consisting of sulfur monochloride, sulfur dichloride and mixtures thereof, and calcining the resulting inorganic oxide vanadium trichloride composite.

From the foregoing embodiments, it will be noted that the process of the present invention makes use of a particular catalytic composite prepared in a particular manner. Therefore, an essential feature of the present invention resides in the method employed in the preparation of the catalytic composite to be disposed Within the reaction zone as a fixed-bed. The catalyst can be characterized as comprising vanadium trichloride in an amount of from about 1.0% to about 30.0% by weight, calculated as elemental vanadium, and a refractory in organic oxide carrier material of either synthetic, or nae tural origin, which carrier material has a medium to high surface area and a well-developed pore structure. The precise composition and method of manufacturing the carrier material is not considered to be a limiting feature of the present invention, although the preferred carrier material, in order to have the most advantageous pore structure, will have an apparent bulk density of less than about 0.35 grams/cc, and preferably within the range of from about 0.10 to about 0.30 grams/cc. 'Furthermore, the refractory inorganic oxide carrier material is preferred to contain at least a portion of alumina, and preferably a composite of alumina and silica, with alumina being in the greater proportion. In many instances, however, other refractory inorganic oxides may be employed in conjunction with the alumina, and include silica, zirconia, magnesia, titania, boria, strontia, hafnia, and mixtures of two or more. By way of examples, a satisfactory carrier material may comprise equimolar quantities of alumina and silica, or 63.0% by weight of alumina and 37.0% by weight of silica, or a carrier of 68.0% by weight ofalumina, 10.0% by weight of silica and 22.0% by weight of boron phosphate. The refractory inorganic oxide carrier material may be formed by any of the numerous techniques which are rather well defined in the prior art relating thereto. Such techniques include the acid-treating of a naturalclay, sand or earth, coprecipitationor successive precipitation from hydrosols, which techniques are frequently coupled with one or more activating treatments including hot oil aging, steaming, drying, oxidizing, reducing, calcining, etc. The pore structure of the carrier, commonly defined in terms of surface area, pore diameter and pore volume, may be developed to specified limits by any means including aging the hydrosol and/or hydrogel under controlled acidic or basic conditions, or by gelling the carrier at a critical pH or by treating the carrier with various inorganic or organic reagents. An adsorptive hydrogenation catalyst, adaptable for utilization in the process of the present invention, will comprise a carrier material having a surface area of about 50 to about 700 square meters/ gram, a pore diameter of about 20 to about 300 Angstroms, a pore volume of about 0.10 to about 0.80 milliliter per gram and an apparent bulk density within the range of from 0.10 to about 0.35 gram/cc.

The catalyst is prepared by initially forming an alumina-containing refractory inorganic oxide material having the foregoing described characteristics. For example, an alumina-silica composite, containing about 63.0% by weight of alumina is prepared via the .coprecipitation of the respective hydrosols. The precipitated material, generally in the form of a hydrogel, is driedat a temperature of about C. and for a time sufficiently long to remove substantially all of the physically-held water. The composite is then subjected to a high-temperature calcination technique in an atmosphere of air, for a period of about one hour at a temperature above about 300 C., which technique serves to remove the greater proportion of the chemically-bound water. The calcined carrier material is combined with vanadium trichloride by way of an impregnation technique utilizing a decomposable vanadium compound, including, but not by way of strict limitation, vanadium carbonyl, vanadyl acetylacetonate, phosphovanadic acid, vanadyl ethyl xanthate, vanadium esters of alcohols, ammonium vanadate, various mixtures thereof, etc. The vanadium compound, or mixtures of compounds, is utilized in an amount such that the final catalytic composite comprises from about 1.0% to about 30.0% by Weight of vanadium, computed on" the basis of the elemental metal. In those instances where the vanadium compound is not Water-soluble at the temperature employed in the impregnation technique, other solvents may be utilized including alcohols, esters, ketones, aromatic hydrocarbons, etc. The impregnated alumina-silica composite is dried at a temperature less than about C., and preferably within the range of about 100 C. to about 150 C. It is preferred that the catalyst preparation technique involves drying the impregnated carrier material at a temperature such that no decomposition occurs; in other Words, the dried, impregnated carrier material will have distributed therein the decomposable vanadium compound. I

The unoalcined, dried, impregnated composite may be stored indefinitely until such time as it will be further treated in accordance with the method of the present invention. The decomposition of the vanadium compound is effected by treating the dried, impregnated carrier material with a sulfurous compound selected from the group consisting of sulfur monochloride, sulfur dichloride and mixtures thereof, and calcining the resulting inorganic oxide-vanadium trichloride composite. The treatment with the sulfurous compound is effected at a temperature not higher than the boiling point of the sulfurous compound employed. That is, the treatment with sulfur dichloride is effected at a temperature not higher than 59 C., whereas the treatment with sulfur monochloride is effected at a temperature not higher than 138 C. In this manner, the decomposable vanadium compound is converted to vanadium trichloride within and throughout the carrier material, and it is believed that the same exists as a particular form of complex with the alumina and silica. The excess sulfur dichloride and/or sulfur monochloride may be removed from the inorganic oxidevanadium trichloride catalyst by the rather simple expediency of sweeping the catalysts with an inert gas including nitrogen, argon, carbon dioxide, etc. The treated composite is then subjected to calcination at a temperature within the range 'of about 150 F. to about 500 F.

Although the precise character of the catalytic composite, following the decomposition of the vanadium compound utilizing sulfur monochloride, sulfur dichloride and/or mixtures thereof, is not known with accuracy, it is believed that the resulting vanadium trichloride forms a new complex with the component and/or components of the refractory inorganic oxide carrier material. In a copending application, I have described a slurry-type process for hydrorefining petroleum crude oils and the heavier hydrocarbon fractions derived therefrom. In this slurry-type process, vanadium trichloride is admixed with the hydrocarbon charge stock, the mixture being subjected to hydrorefining conditions which convert pentaneinsoluble asphaltenic material into pentane-soluble liquid hydrocarbon products. The vanadium trichloride, when utilized in the slurry-type process, indicated an unusually high degree of activity with respect to the conversion of asphaltenic material. I have now found that a suitable hydrorefining catalytic composite, containing vanadium trichloride, can be prepared, and permits effecting the hydrorefining process in a fixed-bed operation, which operation is a preferred petroleum processing technique. Heretofore, a great difficulty has been experienced in obtaining a catalytic composite in which the vanadium trichloride is complexed with components of the carrier material. An impregnating technique, utilizing an aqueous solution of vanadium trichloride cannot be employed due to the fact that the vanadium trichloride decomposes in water. Although an alcohol, or ether solution of vanadium trichloride does not result in decomposition of the vanadium trichloride, the drying step following the impregnation technique, does effect the decomposition of the vanadium trichloride. In accordance with the method of the present invention, the carrier material is impregnated with a decomposable vanadium compound, the decomposition of which is effected in such a manner as to produce vanadium trichloride as the decomposed product, which vanadium trichloride takes the form of a complex with the other components of the carrier material. As hereinabove set forth, a sulfurous compound selected from the group consisting of sulfur monochloride, sulfur dichloride and mixtures'thereof, is employed at its boiling point in treating the impregnated carrier material to effect the decomposition of the organovanadium compound.

The hydrorefining process, utilizing the catalyst prepared in accordance with the method of the present invention, may be effected by initially admixing the hydrocarbon charge stock with hydrogen in an amount within the range of about 5,000 to about 50,000 s.c.f./bbl. of liquid hydrocarbons. The mixture is heated to a temperature of from about 225 C. to about 500 C., and passes into the reaction zone maintained under an imposed pressure within the range of about 500 to about 5,000 p.s.i.g. The hydrocarbon charge stock contacts the catalyst at a liquid hourly space velocity (defined as volumes of liquid hydrocarbon charge per hour per volume of catalyst disposed within the reaction zone) of from about 0.5 to about 5.0. The precise operating conditions, including temperature and pressure, are at least partially dependent upon the physical and chemical characteristics of the hydrocarbon charge stock, the length of the period during which the catalyst has been functioning, and the desired end result. It is understood that the operating conditions, under which the catalytic composite of the present invention is employed, are not limiting upon the scope of the appended claims.

The following example is given for the purpose of illustrating the method by which the catalyst of the present invention is prepared, and the benefits afforded the hydrorefining of heavy hydrocarbonaceous material through the utilization thereof. The charge stocks, temperatures, pressures, catalyst, rates, etc., are herein presented as being exemplary only, and are not intended to limit the present invention to an extent greater than that defined by the scope and spirit of the appended claims.

Example The charge stock utilized in illustrating the process of the present invention is a topped Wyoming sour crude oil. The natural crude oil, having a gravity of 23.2 API at 60 F., is contaminated by the presence of 2.8% by weight of sulfur, approximately 2700 p.p.m. of total nitrogen, p.p.m. of metallic porphyrins (computed as if the metallic component existed as elemental nickel and vanadium), and contains a high-boiling, pentane-insoluble asphaltenic fraction in an amount of 8.39% by weight of the total crude oil. The topped crude oil indicates a gravity, API at 60 F., of 19.5, and contains 3.0% by weight of sulfur, about 2900 p.p.m. of total nitrogen, p.p.m. of nickel and vanadium, the pentane-insoluble asphaltenic fraction being about 8.5% by weight. w

The catalytic composite is a spray-dried alumina-silica carrier material containing about 63.0% by weight of alumina on a dried basis. The carrier material is prepared by initially precipitating, at a constant acidic pH of about 8.0, a blend of acidulated water glass and aluminum chloride hydrosol, with ammonium hydroxide. The resulting hydrogel is washed free of sodium ions, chloride ions, and ammonium ions, and is subjected to spray drying. The spray-dried composite is oxidized, or calcined in an atmosphere of air for a period of about one hour at a temperature of about 550 C. An impregnating solution is prepared utilizing isopropyl alcohol and vanadyl acetylacetonate, the latter in an amount to produce a final catalytic composite comprising about 10.0% by weight of vanadium, calculated as the elemental metal. The alumina-silica carrier material is impregnated with the alcoholic solution of vanadyl acetylacetonate, and dried at a temperature of about 100 C. for a period of about two hours; the drying temperature is controlled such that sudden temperature rises to a level above about C.-, at which temperature the vanadyl acetylacetonate would decompose, is avoided. The dried composite, having a particle size ranging from 20 to about 150 microns, is disposed as a fixed bedin a reaction zone in an amount of about 200 grams. The catalyst is treated with sulfur monochloride at a temperature of 138 'C., by passing nitrogen over sulfur monochloride at its boiling point, the gaseous mixture then passing into the reaction zone in contact with the catalyst disposed therein. After a period of about two hours, the boiling sulfur monochloride is bypassed, the nitrogen stream continuing through the bed of catalyst until such time as the exit gases indicate an absence of sulfur monochloride. The temperature is increased to a level of about 350 F., and the composite of alumina-silica-vanadium trichloride calcined at the elevated temperature in the presence of air.

After a period of about two hours, a hydrogen stream replaces a nitrogen stream which has been used to displace free oxygen from the reaction zone, While the temperature is increased to a level of about 350 C. When the temperature level is reached, the hydrogen is admixed with the previously described topped Wyoming sour crude oil, in an amount of about 25,000 s.c.f./bbl. of liquid charge, a compressor being utilized to maintain the pressure within the reaction zone at about 1,500 p.s.i.g.

The reaction products from the reaction zone are continuously cooled and passed into a high-pressure separator from which a liquid hydrocarbon product is removed to a receiver, the hydrogen-rich gas stream removed through a water scrubber and recycled to the reactor. In order to compensate for the quantity of hydrogen consumed within the process, and absorbed by the normally liquid product efiluent, fresh hydrogen is added to the recycle gas as determined by the operating pressure within the reaction zone, and in this instance, being in an amount of about 2,000 s.c.f./bb1. For approximately one-half of its effective, acceptable life, the catalytic composite of alumina-silica-vanadium trichloride will promote the necessary hydrogenation/hydrocracking reactions to produce a normally liquid product substantially free from pentane-insoluble asphaltenes, organo-metallic contaminants, sulfurous and nitrogenous compounds. Thus, the normally liquid product eflluent will contain less than about 0.5% by weight of pentane-insoluble asphaltenic material, less than 0.5 ppm. of organo-metallic compounds, less than 50 ppm. of total nitrogen and less than about 0.50% by weight of sulfur, the gravity thereof, API at 60 F., being within the range of about 30.0 to about 32.0. As hereinbefore set forth, the presence of excessive quantities of pentane-insoluble asphaltenes as well as organo-metallic compounds, interferes with the capability of the catalyst to effect the destructive removal of nitrogenous and sulfurous compounds. Therefore, the catalyst will indicate a normal activity decline through an increase in the concentration of residual sulfurous and nitrogenous compounds in a normally liquid product effluent. However, since the pentane-insoluble asphaltenes and organo-metallic compounds will be within the previously determined range of less than 0.5% by weight and 0.5 p.p.m. respectively, the operation may be continued on an economic basis notwithstanding a comparatively high concentration of residual, nitrogenous and sulfurous compound. In this situation, the normally liquid product effluent is subjected to a second stage of operation at significantly more sever conditions for the purpose of effecting the complete destructive removal of the remaining sulfurous and nitrogenous compounds. As a result of the natural deterioration of the catalyst component, due to an extended period of operation during which the highly contaminated charge stock comes into contact with the catalyst, regeneration may eventually be required as the above-stated acceptable limitations on residual asphaltenes and metallic contaminants are exceeded. Regeneration is accomplished by the rather simple expediency of initially removing coke and other carbonaceous material from the catalyst by burning in air at a temperature within the range of from about 900 F. to about 1,200 F. Following the removal of coke from the catalyst, it may be treated in situ with sulfur monochloride, sulfur dichloride and mixtures thereof at a tem perature not exceeding the boiling point of sulfur monochloride, or 138 C. In this manner, the vanadium com ponent of the catalyst is reconstituted within the carrier material as vanadium trichloride, and the catalyst is again suitable for utilization in the hyrorefining of petroleum crude oil.

Thus the method of the present invention is a multiplestage regenerative process which, as will be recognized by those possessing skill within the art of petroleum leads directly to clean gasoline and diesel oil, the latter being sufliciently decontaminated to be used immediately as a diesel, jet or fuel oil.

I claim as my invention:

1. A method of preparing a hydrorefining catalyst which comprises impregnating a refractory inorganic oxide with a decomposable vanadium compound, treating the impregnated inorganic oxide with a sulfurous compound selected from the group consisting of sulfur monochloride, sulfur dichloride and mixtures thereof, and calcining the resulting inorganic oxide-vanadium trichloride composite.

2. The method of claim 1 further characterized in that said vanadium compound is ammonium vanadate.

3. The method of claim 1 further characterized in that said vanadium compound is an organo-vanadium compound.

4. The method of claim 3 further characterized in that said organovanadium compound is vanadium xanthate.

5. A method of preparing a hydrorefining catalyst which comprises impregnating a siliceous, alumina-containing inorganic oxide with ammonium vanadate, treating the impregnated inorganic oxide with a sulfurous compound selected from the group consisting of sulfur monochloride, sulfur dichloride and mixtures thereof, and calcining the resulting inorganic oxide-vanadium trichloride composite.

6. The method of claim 5 further characterized in that said impregnated inorganic oxide is treated with sulfur monochloride at a temperature not above 138 C.

7. The method of claim 5 further characterized in that said impregnated inorganic oxide is treated with sulfur dichloride at a temperature not above 59 C.

8. A method of preparing a hydrorefining catalyst which comprises impregnating a composite of silica and alumina with ammonium vanadate, treating the impreg nated composite with sulfur monochloride at a temperature not above 138 C., and calcining the resulting alumina-silica-vanadium trichloride composite at a temperature within the range of from about F. to about 500 F.

9. A hydrorefining catalyst comprising a complex of an alumina-containing inorganic oxide and vanadium trichloride, prepared by impregnating an alumina-containing inorganic oxide with a decomposable vanadium compound, treating the impregnated inorganic oxide with a sulfurous compound selected from the group consisting of sulfur monochloride, sulfur dichloride and mixtures thereof, and calcining the resulting inorganic oxide-vanadium trichloride composite.

References Cited by the Examiner UNITED STATES PATENTS 2,911,359 11/1959 Hansford 20843 3,052,622 9/1962 Johnson et al. 208-213 3,180,820 4/1965 Gleim et al 208--210 3,210,293 10/1965 OHara 252-464 DELBERT E. GANTZ, Primary Examiner. S. P. JONES, Assistant Examiner. 

1. A METHOD OF PREPARING A HYDROREFINING CATALYST WHICH COMPRISES IMPREGNATING A REFRACTORY INORGANIC OXIDE WITH A DECOMPOSABLE VANADIUM COMPOUND, TREATING THE IMPREGNATED INORGANIC OXIDE WITH A SULFUROUS COMPOUND SELECTED FROM THE GROUP CONSISTING OF SULFUR MONOCHLORIDE, SULFUR DICHLORIDE AND MIXTURES THEREOF, AND CALCINING THE RESULTING INORGANIC OXIDE-VANADIUM TRICHLORIDE COMPOSITE. 